That's a very broad question. Have a look at this site's (as well as others) species profiles and see if there are any fish that look/sound good to you. What size tank(s) do you have?
Gourami's are very pretty, as are Rainbowfish. A nice school of Congo or Neon Tetras is always effective, too. I recommend going to several (at least two) pet/fish stores and seeing what catches your fancy. This also helps you compair prices.